Here is a summary of the conference about the CZZ deposits.
I have highlighted the most surprizing content to me.
The South Raglan trend constitutes a series of magmatic Ni-Cu-PGE sulfide deposits and showings along approximately 100 km strike length running parallel to the currently producing deposits of the main Raglan trend. The two most significant occurrences are the Expo-Ungava deposit and the Mesamax deposit.
The Expo-Ungava deposit is a 15 Mt resource grading 0.6% Ni and 0.8% Cu and estimated to contain 1 to 3 g/t of Pd. The resource at Mesamax consists of 1.45 Mt of massive to disseminated sulfide mineralization hosted by pyroxenite and grading 2.1% Ni, 2.7% Cu, 0.3 g/t Au, 1.0 g/t Pt and 4.2 g/t Pd. Mineralization consists of massive pyrrhotite, pentlandite, chalcopyrite and magnetite, or of disseminated pyrrhotite, pentlandite and chalcopyrite.
Evolution of the sulfides is consistent with nearly complete equilibrium crystallization of monosulfide solid solution from sulfide magma followed by outward migration of fractionated sulfide melts rich in Cu, Pd, and Au to form extremely Pd-rich selvedges around bodies of massive sulfide. Mineralization is hosted by irregularly zoned mafic to ultramafic intrusive bodies hosted by metasediments and metavolcanics of the Povungnituk Group in the New Quebec Orogen.
Whereas preliminary fieldwork led to the interpretation that the mineralized ultramafic rocks were channelized flows belonging to the Povungnituk Group, extensive mapping in 2003 has shown that they are sharply discordant magmatic conduits in all cases. Mineral fabrics, metamorphic grades, detailed drill sections and map patterns show that the entire South Raglan trend can be interpreted as a series of en echelon or parallel dikes trending approximately N70E, which can collectively be termed the Expo Dikes. The Expo Dikes were emplaced into the New Quebec Orogen after the development of km-scale open folds in the metasedimentary and metavolcanic supracrustal succession and after their host rocks had cooled from peak metamorphic conditions. Post-emplacement metamorphism has largely replaced primary phases with a greenschist mineral assemblage, but some large masses of gabbro-norite and pyroxenite remain very fresh. Locally intense ductile shear produced greenschist facies assemblages and is associated with a later deformational episode.
Although the overall similarity of the mineralization in the Expo Dikes invites correlation with the Raglan trend, the grossly different Cu/Ni ratios (1.0 in the Expo Dikes, 0.3 at Raglan) suggest that the two suites are unrelated. The timing of emplacement of the Expo Dikes is problematic and may require re-evaluation of the tectonic evolution of the New Quebec Orogen. |
